paryGdzieSuma13

public class Pair {
    public static void getPairsCount(List<Integer> numbersList,int n, int sum) {
        for (int i = 0; i < n; i++)
            for (int j = i + 1; j < n; j++)
                if (numbersList.get(j) + numbersList.get(i) == sum)
                    System.out.println(numbersList.get(j) + " " + numbersList.get(i));
    }
    public static void main(String[] args) {
        List<Integer> numbersList =  Arrays.asList(1, 2, 10, 7, 5, 3, 6, 6, 13, 0);
        int sum = 13;
       int n=numbersList.size();
        getPairsCount(numbersList,n, sum);
    }
}